"NEW - Never Ever Works"
- Eric @ South Main Auto

I occasionally do a bit of work in a diagnostics garage, car comes in, runs like poo, - has 6 main codes set, 5 of them were caused by "NEW" ebay after market parts trying to fix the first one!

 

Hi, as it happens I had exactly the same, and I mean every single message you get on your " scroll of death" on my 1997 4 litre XK8 I checked every connection, fuse, inertia switch ,relay etc etc. I unplugged every module one at a time but always the same messages and no start. The last thing I disconnected was the gearbox rotary switch and the scroll vanished and the engine started but obviously wouldn't drive until I fitted a used rotary switch from ebay for about £40 and no problem since!
It's well worth a try and it's an easy 2 minute job to unplug it. In case you don't know where it is it is near the bracket on the top of the gearbox that holds the lambda sensors plugs

 

I had the same codes today (first time I ever saw the "incorrect part fitted") and my XK8 would not start. Disconnected battery, reconnected and then used OBD reader to erase codes..and it started and all codes were gone. I've used the OBD reader many times to erase codes. It's well known that these cars throw bogus codes. Now WHY this happens is, to my knowledge, not known. But when you get lots of digital boxes and a digital bus around ignition noise and other EMI/RFI crap it doesn't surprise me.
The other problem is the battery and it's connections. Why the car is so touchy seems to be a mystery. I put a new AGM in and it seems to be better than the old flooded lead-acid; fewer codes.